[GT-AC5300] Outgoing port selective blocking

[69boss302]

Hello. Ive been using a GT-AC5300 for some time now and I love it. Im trying to figure out how to block outgoing ports for everything other than 1 host.

Reason:
I have my own mail server which speaks SMTP (port 25) but it seems someone on the LAN has a virus and is spamming the world, therefore putting my IP on blacklists. Id like to be able to only allow my mail server to use outgoing port 25, and block all other devices from using that port. I dont see where I can do that.

Thanks for any input!

 

[ColinTaylor]

Firewall - Network Services Filter

 

[69boss302]

I dont seem to be doing it right, can you give me an example?

 

[ColinTaylor]

How are you determining that it's another device on your LAN that is the cause of the problem? The most common scenario is that you have mis-configured your mail server and it is being used as a relay by malicious devices out on the internet. In that case blocking port 25 for other LAN devices won't help as it is your mail server that's the problem.

 

[69boss302]

Because I always test my mail server, it is not an open relay, and for testing we shut down the entire mail server and still had the issue.

 

[69boss302]

Its been another week and I still am unable to block outgoing ports. Anyone have any ideas?